doc: Corrections for gnutls_handshake_set_hook_function()
coding style: update the DCO text
Added flag GNUTLS_PKCS11_OBJ_FLAG_MARK_CA.

That flag allows to mark a certificate in the token as a CA (category==CA)
p11tool: Allow marking a certificate as a CA.
gnutls_x509_trust_list_add_trust_file(): returns the number of certificates present when loading a PKCS #11 URL.
Test the return code of gnutls_x509_trust_list_add_trust_file() when loading a PKCS #11 token.

Check whether the return code of gnutls_x509_trust_list_add_trust_file() is non-zero
when certificates are present.
doc update
treat the _gnutls_user_hello_func() output the same on resumed sessions.
gnutls_packet_get() was introduced to avoid exporting a structure on the API.

That change will allow exporting more info associated with a packet in the future.